StyledEdit - Add function to reload a document (ticket #6887)

The goal of this task is the implementing correct solution for features required in Haiku Trac as ticket #6887. This is a coding task, for this task you will need to have a Haiku build environment setup, and be able to compile either Haiku or standalone StyledEdit project to fix the problem and check if your solution works. The basic knowledge of GIT SCM is also needed.

Requirements:

Install Haiku either on real hardware or in Virtual Machine (BTW, I can assist installing VirtualBox so it is obviously recommended by me);

Take familiar with the problem you should fix;

Get either the Haiku source tree or standalone StyledEdit project sources build it and find solution to fix the problem;

Note that fix should include "Reload with encodings" feature requested in latest comments. Node monitoring is also should be implemented;

After completing this task, please provide us with the git-formatted patch of implemented features.